Patients with respiratory insufficiency often require continuous mechanical ventilation with a positive-pressure ventilator. In such patients, an endotracheal breathing tube, or a tracheotomy tube, is positioned in the patient's main airway. An internal end of the endotracheal breathing tube is positioned for exchange of air within the lungs and an externally protruding end of the endotracheal breathing tube is connected with a ventilator circuit of a ventilator system. The ventilator system provides heated, humidified, filtered breathable air at a prescribed respirable rate, tidal volume or pressure, and FiO2 to a patient in repetitive respiration cycles.
It is frequently necessary to use a Metered Dose Inhaler (“MDI”) to deliver a prescribed amount of an aerosolized drug into an air stream that is forced through an inspiratory phrase of a ventilator system. In the present practice, to engage a MDI ventilator assembly with a ventilator circuit, an inspiratory hose is disconnected from a ventilator at a Wye connector, and the MDI ventilator assembly is used to reconnect the inspiratory hose to the Wye connector. The aerosolized drug is dispensed into an inspiratory stream, and upon completion of the therapy, the MDI ventilator assembly is removed from the inspiratory side of the ventilator circuit.
There are a number of problems with this practice. For example, due to the distance from an inspired limb of a ventilation circuit to an end of an endotracheal tube leading to a patient, loss of the aerosolized drug dispensed in the inspired limb often occurs before reaching the patient.
Another problem with present MDI ventilator assemblies is that they may not be attached directly to an endotracheal tube and left in connection to a main ventilator circuit because it presents a “dead space area” where gases exhaled from a patient remain between each breath such that the same gases are inhaled by the patient upon their next breath. For example, neonates often require aerosol medication, which can be difficult to administer due to the small airway size and because ventilation is required immediately after birth.
In addition, it is desirable to provide for aerosol medication delivery in conjunction with a resuscitation bag, which may be connected to an oxygen supply. Importantly, such systems must maintain a positive-end expiratory pressure (PEEP) for patients that have been intubated.
For at least these reasons, improved MDI ventilator assemblies are desirable.